When utilizing time-space-position information (TSPI) instrumentation, an inertial movement unit (IMU) is used to track movement changes. If the IMU measurement is located in an offset position by anything more than about 5 centimeters (2 inches), TSPI accuracy is compromised. Setting up IMU alignment is a complex effort requiring accurate measurements from the IMU to GSP antennas, the IMU to a defined navigation point, the IMU to a HT-DLTA, the IMU to a HT-DLTB, the IMU to PP, and the combination of these devices to an aircraft. Increasing the accuracy of these measurements produces more accurate TSPI measurements.
When performing an automated zone accuracy for lever-arm and Euler-angle alignment (AZALEA) process, the angles of incidence from laser distance measurements need to be recorded to determine the actual location in 3D space. Setting up spatial data for AZALEA needs highly accurate angle data from probe points. If a 3rd point is drawn in physical space, outside of the apparatus being measured, and a laser distance measurement is utilized, the receiver receives extremely accurate angle measurements.
Any error in any of these measurements creates persistent erroneous data.